ULiège gets involved to reduce its consumption

World Water Day is celebrated every 22 March. This day is a reminder that 11% of the world's population does not have access to drinking water and that even in Wallonia, the risk of water scarcity due to climate change is likely and could reduce the quality of surface water.

Water consumption in a few figures

• A Walloon consumes an average of 120 litres of water per day, which places it among the most thrifty of the Europeans (average of 200 litres/day) and even of the 'developed' countries where consumption can exceed 250 litres per day. According to a Belgian consumer association, the breakdown of water consumption in a household is as follows
  • 35% for the WC,
  • 33% for personal hygiene,
  • 13% for laundry,
  • 10% for food preparation and washing up,
  • The remainder is divided equally between cleaning and gardening.
• The transport efficiency of water systems generally varies between 70 and 85%^[1][2]. This means that for every cubic metre delivered to a building, between 150 and 300 litres are lost "to nature". The private network of the Sart Tilman is a good example, as the identified efficiency is 90%.
• A water leak can quickly become costly:
  • A drip leak at a sink can represent up to 35 m³ of water per year or about €175;
  • A continuously running toilet flush can account for around 200 m³ per year, bringing the annual cost to over €1000.

Involvement of ULiège

As mentioned in a previous newsletter (Energy and buildings), ULiège reduced its water consumption by almost 60% between 2005 and 2018, from an annual consumption of 19 m³ per person (students and staff) to 8 m³ per person.

This reduction has been achieved by replacing waste water devices^[3], increasing maintenance of its private water network in the Sart Tilman and raising user awareness.

As part of its new maintenance contract (which took effect in December 2018), ULiège has planned to reduce water consumption on the Sart Tilman site by 4%, i.e. more than 8,000 m³, thanks to an ambitious investment plan.

At the same time, in 2019, ULiège has embarked on the monitoring of two pilot installations (Central Building (A1) and the Sart Tilman water network) in order to follow water consumption "in real time" and to diagnose as quickly as possible any malfunctions (such as leaks, etc.). This system replaces the old quarterly readings, which did not allow for rapid detection of drifts in consumption or leaks.

Feedback

In the central building, the feedback from this monitoring campaign is as follows:

• Many defective devices (flushes and taps) were diagnosed and repaired within a week thanks to the continuous monitoring of the installations and the intervention of the ARI Maintenance Unit;
• Sabotage (flushes or taps deliberately blocked in the open position) or oversights on the part of users were also quickly diagnosed and corrected;
• Identification of an inefficient regulation on a group of urinals. A project to refurbish these urinals is planned for 2021 in order to reduce their consumption by 30 to 50%.

At Sart Tilman, three large-scale incidents were diagnosed and quickly resolved^[4]:

• Break in a pipe by a construction machine belonging to an external company (120 m³/h);
• Opening of a valve by users supplying a section of the water network closed for maintenance (12 m³/h);
• Abnormal consumption after the February thaw (broken tap) (5 m³/h).

Perspectives

On the basis of this experience, the Planning - Energy and Environment Unit plans to instrument more than 20 additional water meters on the Sart Tilman site and in the city in 2021 and 2022 in order to identify leaks and act as quickly as possible on their causes.

At the same time, a call is made to building managers, users or local groups involved in sustainable management to identify installations running on waste water^[3] in order to consider their replacement by more efficient alternatives.

Advice

For private use, it is advisable to carry out a preliminary check of your water infrastructure by visually/audibly identifying the presence of leaks.

It is also advisable to read the meter before and after a period of several hours without consumption (night or working day) in order to identify a leak: indeed if the meter has "risen" while you were away or no water point was used, it is likely that a leak is present (or at least an appliance consumes water). These actions will obviously only reflect a snapshot of your installation, which is why it is advisable to read your main water meter once a quarter in order to identify abnormal water consumption as soon as possible. Commercial devices also exist to measure water consumption in "real time" and warn the user of abnormal consumption. In some cases, it is even possible to cut off the water supply to avoid collateral damage in case of a major leak.

To conclude this article, here are some tips for reducing water consumption:

• Use (short) showers instead of baths:
  • A bath is between 100 and 150 litres, whereas a 5-minute shower uses about 50 litres (flow rate of 10 litres/minute);
  • To help you avoid taking long showers, install a timer (like those found in the kitchen) to warn you of the duration of your shower;
  • Turn off the water tap when soaping;
• Use an energy-saving shower head or a mousseur to limit the flow of water and thus the total consumption of the water point;
• Turn off the tap when brushing teeth and/or use a cup;
• Choose water-saving appliances (washing machines/dishwashers). These are usually also more energy efficient;
• Watering:
  • Preferably with a watering can to target only the roots and not water a whole area unnecessarily;
  • In the evening to prevent some of the water from evaporating;
  • Make sure the soil is loose so that the water can soak in and not percolate;
  • Use mulch (e.g. grass clippings or leaves) to cover the ground where your plants are not located to reduce soil evaporation;
  • Recuperate water from your daily uses (rinsing vegetables, cooled cooking water, cold running water while waiting for it to be hot for washing dishes or showering, ...) to water your plants;
• Use rainwater to supply the WC or even the washing machine (filtering it beforehand);
• Consider dry toilets.